Definition: You are given a math word problem and you are supposed to make use of mathematical concepts like probability, combinatorics, linear equations, sequences/series, or simple operators like addition, subtraction, division, or multiplication to answer the given question. Choose the best option from the 5 given options and report that option.
Input: Question: If 18 is 15 percent of 30 percent of a certain number, what is the number?

 Option A: 9

 Option B: 36

 Option C: 40

 Option D: 81

 Option E: 400

Option E